A nuclear explosion poses a multitude of problems to human existence. Subsequent to the initial shock waves and the incendiary effects of the initial heat waves, the combined effects of nuclear fallout and the settling of unbreathable, heavier-than-air gases in low areas surrounding the explosion produce great risks for humans inhabiting those areas. Primarily, such unbreathable gases comprise large quantities of carbon dioxide generated by the massive conflagration created by the explosion.
Nuclear radiation is produced by the spontaneous nuclear decay and transformation of materials and elements exposed to the nuclear explosion. The process of decay or transformation emits great amounts of energy in the form of alpha, beta or gamma rays. This energy-emitting process is termed "radioactivity," and, depending on the energy and/or wave length of the particular wave or ray involved, human exposure to radioactivity causes varying degrees of sickness and even death.
Alpha rays are produced by the spontaneous emission of helium nuclei from radioactive elements. A continuous stream of such helium nuclei forms the alpha ray. The alpha particles forming the alpha ray are easily dissipated by thin layers of shielding such as a few centimeters of air or less than a millmeter of aluminum. Without shielding the rays do not penetrate beyond the superficial layers of the skin.
A beta ray is a continuous stream of electrons emitted from a radioactive or decaying atomic nucleus. Since an electron has a much smaller mass than a helium nucleus, the beta particles forming the beta ray have a much smaller mass than the alpha particles forming the alpha ray. Due in part to this smaller mass, beta rays can penetrate somewhat further than alpha rays, but in any event may be stopped by a few millimeters of lead or other dense material or a somewhat greater amount of air than is required to absorb alpha rays. Even without shielding, beta rays would be absorbed in the outer layers of skin and would not reach internal organs.
Gamma rays are not formed by the emission of small particles of mass, but are extremely penetrating electromagnetic radiation having extremely short wave lengths and high energy. Gamma rays also originate in the atomic nucleus and usually accompany alpha and beta emission. A great deal of shielding is necessary to absorb gamma rays. The highest energy gamma rays will even penetrate several centimeters of lead shielding. However, gamma rays can be absorbed by sufficient thicknesses of concrete and earth as well as by sufficient thicknesses of lead. Without shielding, gamma rays do great harm to the human body since they penetrate the body affecting internal organs and bones. Thus, although alpha and beta rays may be completely dissipated by several feet of air and/or an intermediate layer of another material, gamma rays, and especially high energy gamma rays, require significantly greater thicknesses of shielding materials.
In order to avoid such radiation, people would move into their basements. This, however, exposes them to a second danger. After a nuclear explosion, the heat and incendiary effects of the explosion produce great amounts of carbon dioxide. Carbon dioxide is heavier than air and thus will settle in depressions and low spots, such as basements, in the areas surrounding the blast. Since carbon dioxide is tasteless, colorless and odorless, there is little or no warning to persons who take shelter from radiation effects in cellars, basements or other low protected area. In this connection, it is well to realize that the basement of an individual dwelling will provide the greatest protection against the highly penetrating gamma rays due to the thicknesses of the walls and earth surrounding the house. Consequently, the escape from radioactivity may end in suffocation.